1. Field of the Invention
The present invention relates to a self loading and self sealing, disposable allergy testing apparatus.
2. Description of the Prior Art
Allergy testing involves subjecting a patient to a wide variety of different allergens to determine which allergens cause allergic reactions in the patient. Such testing requires that the respective allergens be applied beneath the surface of the patient's skin. There are two methods of intracutaneous allergen application, the first being the puncture method and the second abrasion. Ideally an allergen applicator should be capable of use in either the puncture or abrasion techniques, because skin thickness or toughness varies from patient to patient. The puncture method is accomplished by piercing the patient's skin with sharply pointed prongs while applying a drop of allergen. The second method, abrasion, involves abrading the skin through a drop of allergen using an abrading or scarifying device such as a sharp knife or chisel like instrument.
These abrading techniques can be satisfactorily performed only by technicians having considerable experience and sensitivity to the allergen used and the skin of the patient, as well as familiarity with the tool. Different technicians performing the same tests oftentimes do not achieve the same results because the intensity and penetration of the abrasion and amount of allergen introduced into the skin varies from patient to patient and is highly dependent on the particular manner in which the technique is carried out. The degree of variation is compounded by the fact that different patients possess different skin thickness and sensitivity.
The allergen, remaining in the vial, being expensive and sensitive to environmental exposure, should be conserved for subsequent application. Therefore, it is desirable that the allergen be stored in a container which can be easily sealed after use, and which will collect the residual allergen for effective use in subsequent applications. It is desirable that the pick be constructed to facilitate extraction of the residual allergen from the container and to subsequently seal the container without requiring inordinate manual dexterity or the use of extraneous tools. Since it is often desirable to vary the number of allergens tested on any particular patient, it would be preferable to be able to easily vary the number and type of allergen containers in a set to provide the technician the flexibility of varying the number of allergens in such set.
One device proposed for the delivery of allergen involves the use of a pick including a single, hollow cylindrical chisel to create capillary action when the chisel is submersed within the allergen. The hollow cylindrical bore is effective in allowing the device to hold the proper amount of allergen, and this device has been successfully used. However, this device is limited to delivering allergen to only one point within the patient's skin, limiting the amount of allergen which can be applied to the patient's skin. Also, because the device does not limit the depth of penetration of the chisel, dispensing the allergen to the proper depth within the patient's skin requires certain degree of skill on the part of the technician. This form of allergen applicator can be found in U.S. Pat. No. 4,304,241.
Another device proposed by the prior art is a single cylindrical stem formed at its bottom end with a bifurcated point to define a pair of blades. A device of this type has been marketed by Center Laboratories under the trademark DUOPICK-TEST.RTM.. Such devices suffer the shortcoming that they are awkward and inconvenient to handle and manipulate and are difficult to store. They fail to include any plug or support member or cover which might cooperate in holding the device erect, centered and sealed in a vial for convenient access. Moreover, with only two tines, the quantity of allergen which can be administered is limited.
One very commercially successful device, previously sold under the trademark DERMAPIK, incorporated an antigen assembly including a tray configured with upwardly opening wells dispersed thereabout and closed at their respective top ends by means of stoppers configured with a centrally disposed, severable bubble covering a small diameter entry passage. Thus, in practice, the technician could gain access to allergen stored in the vial by cutting off the bubble tip to create a small opening inserting a small diameter stem of an applicator through the small opening. A device of this type is shown in my U.S. Pat. No. 4,237,906. While having enjoyed great commercial success, such a device has the shortcoming that removal of the bubble cap is time consuming, requires some degree of dexterity and can contribute to contamination of the allergen. Additionally, the relatively close interfitting relationship between the stem and entry opening requires relatively steady nerves on behalf of the technician and some degree of patience for inserting the stem into the passage.
In this regard, the applicator stem shown in my U.S. Pat. No. 4,237,906 incorporates a circular array of relatively short, pyramidal shaped teeth for abrading the patient's skin. Such teeth were of relatively wide cross section at their base and throughout a major portion of their respective axial lengths thus rendering them unacceptable for applications where penetration was to be of any significant depth into the skin. Further, such teeth were not sized or arranged in such a manner as to provide for carrying of a sufficient quantity of allergen of the viscosity presently utilized in the medical field thus limiting its usage to technicians having some degree of experience and skill in performing the procedure.
A similar device has been used which employs a vial and a cap having a reduced in cross section opening. The cap is configured with a reduced in cross section opening and an upwardly extending collar. The collar is sized for receiving and being sealed by the handle of an applicator pick, which is installed within the cap and the stem of which extends into the vial. In use, this device eliminates the need to cut off a bubble top, being sealed by the handle of the applicator fitting within the cap, and therefore reduces the risk of contamination inherent in cutting of the bubble tip. However, as with the previous device, this device suffers the shortcoming of having an opening of relatively small diameter, making installation of an applicator pick difficult.
Several devices have been developed which apply a plurality of allergens simultaneously at predetermined spaced apart locations on the patient's skin. By applying all of the allergens simultaneously, these device are effective in reducing the duration of discomfort of the patient and have been successfully used in situations where the puncture technique has been the desired method of application. However, because allergen is being applied simultaneously at several adjacent locations, the device must be pressed straight down and often rocked back and forth onto the patient's skin, and the individual applicators cannot be twisted about their own axes as is required in the abrasion mode. A device of this type is especially problematic for use on patients having small diameter arms which do not provide a sufficiently flat surface for applying many allergens simultaneously. Devices of this type are shown in my U.S. Pat. No. 5,551,441 as well as in U.S. Pat. Nos. 2,522,309 and 5,154,181.
Still another device proposed includes a base having a set number of upwardly opening wells for receipt of individual picks covered collectively by a single removable cover or to be covered individually by separate well caps. While this device provides convenient access to and secure sealing of the allergen, it fails to provide the convenience and flexibility of providing a holder adapted to receive different sets of vials of allergen which can be changed to accommodate the differing needs of various patients. A device of this sort is shown in my U.S. Pat. No. 5,538,134.
Thus, there exists a need for an allergy testing device which is self sealing, self loading, and disposable with the proper quantity of allergen and which can be used for either a puncture application or abrasion application and with interchangeable vials.